AND-logic circuit with #amplifier

Distribution #box with 4 or 8 sockets;
with built-in signal amplifier,
to connect PNP #sensors in series
and recover any voltage drop.

AND-logic circuit with amplifier - Shield's M8 distributor.

Advantages:

• Led near each M8 socket shows on-off signal status.
• It is possible to put sensors in series with high voltage drop as well.
• Connection of many sensors to the cabinet by a simple 3-pole M12 #connector.
• Single PLC input can get signal from many sensors.

Accessories: special male M8 connector for input exclusion.

#Current-carrying #Capacity. Cable Voltage Drop

Cable choice.
An important element of assessment is the length of the cable. Each meter of the cable causes a voltage drop proportional to the value of the current that runs through it, if cosf = 1 we have: V = IxR.
V = voltage drop, I = current, R = resistance of the cable. In the case of inductive loads (solenoid valves, motors, etc.) or with variable currents, the higher current peak must be considered to avoid even temporary loss of power, which could hinder the proper functioning of the equipment. The longer is the cable, the greater the #voltage #drop, the IEC allows maximum values drop from 3% to 5% of rated voltage. Greater values are admitted only for the current peaks (e.g.: engines starting), if they do not create functioning problems. To minimize the voltage drop the cable section should be increased. Here are some tables that can help to easily calculate the minimum theoretical cable section. See tables 3 and 4 on the page http://www.shield.net/files/catalogue/support/2.2.pdf.
For example, an average continuous current 1 A with section 0,34 mm2 and cable length 10 m generates a voltage drop of 1,3 V, which is approximately 5% of 24 V.

#Cable Maximum Voltage Rating and #Mechanical Strength

Tips to choose a cable.
The maximum voltage depends on the material characteristics, the conductor insulation thickness and the outer sheath thickness. The insulation must be sufficiently resistant to prevent even accidental crushing situations, so different uses can have different requirements of project. Norms as UL and CSA (American), IEC (International) and EN (European) set values which are not always equal to each other and sometimes refer only to heavy employment, such as cables for power transmission.

For the transmission of signals inside industrial machinery, it is frequent to use reduced thickness which refers to commercial standards which are not supported by norms, such as cables LiYY and FROR. The advantage of using reduced thickness is particularly evident in the smaller volume occupied by bundles of cables. The reference nominal voltage is generally at least 300 V. On the market there are also low-cost cables in PVC, with extremely reduced thickness, which may not be compatible with the safety standards for specific applications; it is advisable to carefully evaluate the characteristics of the products.
The norm IEC 60204-1 (#Machinery #Safety) recommends the minimum section of the cables according to the application as well, see table 1 on page http://www.shield.net/files/catalogue/support/2.2.pdf. The norm allows smaller sections only if the mechanical protection is sufficiently guaranteed, for example with conduits.